Tuesday, December 1, 2015

Despite its promise, will gene editing be used as a
legitimate therapeutic tool or as a mere way to manufacture “perfect” designer
babies?

By: Ringo Bones

The promise of effectively curing inheritable diseases and
the dangers of indiscriminately manufactured designer babies is now a step
closer thanks to gene editing – which is an improved version of gene therapy.
Techniques to edit human DNA for therapeutic means have been around for some
time. One method is gene therapy which was already in regular use for the past
15 years. Gene therapy involves using a disabled virus – known as viral vector –
to deliver a synthetic functioning copy of gene into cells. Sadly, this method
has a glaring disadvantage because there is no way for scientists to know where
the gene will end up amidst the billions of letters of DNA code in the nucleus
of cells.

The latest improved method of “gene therapy” dubbed as gene
editing or genome editing offers something far more precise – adding the gene
in an exact location. And unlike older gene therapy methods, gene editing can
also be used to snip out a faulty section of DNA.

There are currently several types of gene editing schemes,
but the technology really took off three years ago when a cheap and efficient
method was developed by Prof. Jennifer Doudna of University of California,
Berkeley and Prof. Emmanuelle Charpentier, now at the Helmholtz Center for
infectious Research in Germany. Known as Crispr-Cas9, it has been adopted by
scientists around the world.

Crisprs (clustered regularly interspaced short palindromic
repeats) are sections of DNA, while Cas9 (crispr-associated protein 9) is an
enzyme. They are found in bacteria which they use to disable attacks from
viruses. Rather like a GPS sat nav, Crispr scans the genome looking for the
right location and then use the Cas9 protein as “molecular scissors” to snip
through the DNA. Prof. Doudna and Prof. Charpentier realized that this bacterial
cut-and-paste system could be used to edit human genes. Almost immediately Crispr
became the gene editing technique of choice because of its speed, accuracy and
simplicity. It has caused a quiet revolution in research labs across the world.
Experiments which once took months can now be done in weeks and the potential
is vast.

Last month, scientists said they had used it to create a
mosquito that can resist malaria. Plant breeders are using Crispr to create
disease-resistant strain of crops. Back in April 2015, researchers in Mainland
China edited human embryos to try to correct a faulty gene that caused an
inherited blood disorder. The embryos used were never destined to be implanted,
but the research rang alarm bells about the implications of gene editing – i.e.
the “specter” of perfect blond blue-eyed designer babies and editing out mental
disorders like manic depression, which unfortunately, is a prerequisite mental
disorder for brilliant poets, authors, musicians and playwrights.